Synchronized Measurements for Monitoring Power Quality in DC Systems: A Proposal

Dc grids and microgrids represent attractive solutions for the integration of renewable energy sources, storage systems and chargers for electric vehicles, all requiring power electronic interface converters. However, there is a severe lack of measurement tools to deal with dc grids, both from a scientific and normative point of view. In this scenario, the present paper proposes to extend remote synchronized measurements, commonly adopted in ac power systems, also to dc distribution. This would enable observing the state of the grid, tracking dynamics and perform power quality monitoring, in particular detecting and measuring the most significant ripple components. In this respect, a possible algorithm, based on a suitably modified Taylor-Fourier Multifrequency model, has been developed. Achieved performance is assessed through numerical simulations that mimic a realistic situation, namely a dc load supplied by a 12-pulse rectifier operating under both steady-state and dynamic scenarios. Results show how the proposed method clearly outperform a conventional DFT-based approach when off-nominal conditions are considered.